1. Field of the Invention
This invention relates to hydraulic hammers and more particularly to a hydraulic circuit for improving operation of a hydraulic hammer mounted remote from the hydraulic supply.
2. Description of the Prior Art
Fluid operated hammers have for a relatively long time been used at the end of a movable boom on various machines. See for example U.S. Pat. No. 2,983,496 issued May 9, 1961. The hammers have an inlet port for receiving the operating fluid and an outlet port from which the fluid is expelled. These hammers which are used for breaking rock, concrete, and the like are adversely affected by back pressure on the outlet port.
Originally, these hammers were pneumatically operated and the outlet port could vent directly to atmosphere. In pneumatic hammers, since the outlet was directly vented to atmosphere, back pressure did not inhibit operation. The operating fluid for the hammer can also be hydraulic. For hydraulically operated hammers the hydraulic fluid cannot be discharged at the outlet port of the hammer but must be returned to a hydraulic supply sump.
Since back pressure at the hydraulic hammer outlet port can adversely affect hammer operation, the return hydraulic lines were required to be of a relatively large size to minimize back pressure. However, since the hydraulic sump is located a substantial distance from the hammer itself, even a relatively large return line provides enough restriction to hydraulic fluid flow so as to cause appreciable back pressure at the outlet port.
It has been recognized that this back pressure problem at the outlet port is a problem with hydraulic hammer operation. Attempts have been made to solve this problem by providing a suction pump at the hydraulic supply sump to more effectively draw the hydraulic fluid through the return line. This approach, however, has not been completely effective and a rather large hydraulic return line from the hydraulic hammer is still required.